摘要:

This paper proposes an adaptive controller for load-frequency control of interconnected power systems. The proposed controller uses a signal synthesis adaptation approach such that the performance of the controlled system is insensitive to the changing load and system parameter variations. It is designed such that only the outputs of the controlled plant are fed back to the controller. A reduced reference model is used to simplify the design, making the controller easier to implement. The effectiveness of the proposed controller is illustrated by digital simulation of an interconnected power system consisting of a hydro plant and a steam plant. The results show that the performance of the proposed controller is comparable with that obtained from a full state feedback optimal controller, and the performance is rather insensitive to the variations of system parameters.

ISSN:0020-7179    

DOI:10.1080/00207179408921510

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper presents a control design for the tip position trajectory tracking of a two-link manipulator arm with a flexible forearm. The control design is based on two steps. First, input-output linearization is applied to decouple the shoulder arm dynamics from the forearm dynamics, which transforms the trajectory tracking control of the nonlinear non-minimum phase system into the trajectory tracking control of two linear subsystems. Then trajectory tracking control design of each subsystem is carried out in the second design step. Stability and performance properties of the control design are presented together with simulation results. This study demonstrates a control design method for trajectory tracking control of a nonlinear non-minimum phase system.

ISSN:0020-7179    

DOI:10.1080/00207179408921511

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The problem of designing a static state feedback or full order dynamic controller is formulated as a problem of designing an appropriate plant state covariance matrix. We show that closed loop stability and multiple output norm constraints imply that the plant state covariance matrix lies at the intersection of some specified closed convex sets in the space of symmetric matrices. We address the covariance feasibility problem to determine the existence and compute a covariance matrix to satisfy assignability and output norm performance constraints. We address the covariance optimization problem to construct an assignable covariance matrix which satisfies output performance constraints and is as close as possible to a given desired covariance. We also treat inconsistent constraints where we look for an assignable covariance matrix which ‘best’ approximates desired but non-achievable output performance objectives (we call this the infeasible covariance optimization problem). All these problems are of a convex nature and alternating convex projection methodologies are suggested to solve them. These techniques provide simple and effective numerical algorithms for a solution of non-smooth convex programs and their presentation in this paper is of particular importance since (to the authors’ knowledge) this is the first time these methods have been used in control design, and they might find wide applicability in several aspects of computational control problems. Expressions for the required convex projections on the assignability and the performance constraint sets are derived. An example illustrates the methodology.

ISSN:0020-7179    

DOI:10.1080/00207179408921512

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

New higher order correlation tests which use model residuals combined with system inputs and outputs are presented to check the validity of a general class of nonlinear models. The new method is illustrated by testing both simple and complex nonlinear system models.

ISSN:0020-7179    

DOI:10.1080/00207179408921513

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A new method is presented for the off-line identification of plant nonlinearities from plant response data. No prior knowledge of the structure of the nonlinearities is required, although a knowledge of the dependent variables within the nonlinearities is assumed. The identification strategy involves the use of Walsh functions which are described in the paper. These functions are particularly suitable for high-speed digital implementation, and are very well suited to dealing with functions with discontinuities. The nonlinear functions identified by this method can be used in a nonlinear plant Walsh function control scheme, which is currently the subject of research. A set of typical implementation results of both identification and control is included, which shows the efficacy of the method.

ISSN:0020-7179    

DOI:10.1080/00207179408921514

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper examines the fundamental system properties of pole mobility and stabilizability under bounded feedback for the case of single-input single-output (SISO) systems, where the constraints on the feedback are defined in terms of theL2norm. It is shown that the bounded gain assumption implies a bounded norm condition on the coefficient vector associated with the closed-loop characteristic polynomial. Classical and new results on the root distribution of bounded coefficient polynomials are reviewed first. With these results, the closed-loop pole mobility of SISO systems under bounded state feedback is studied. It is shown that the assignable closed-loop poles are always within bounded regions, and alternative estimates for these regions are given. Exact boundaries are also established by utilizing computational methods. A common computational scheme is also developed to calculate the distances of stable polynomials from instability and the distance of unstable polynomials from stability. Finally, for open loop unstable systems, the problems of stabilization and δ-stabilization under theL2norm restriction are considered. The minimal norm required for stabilizing or δ-stabilizing unstable systems can be found.

ISSN:0020-7179    

DOI:10.1080/00207179408921515

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Identification and control of nonlinear processes can be achieved using neural networks. However, previous work extending the identification to the on-line adaptive case has resulted in extremely poor performance, preventing practical application in a control framework. The work presented in this paper proposes and demonstrates a powerful method for implementing a neural network model of nonlinear process dynamics for adaptive control. The performance of adaptation has now been sufficiently raised to allow practical adaptive control to be considered. The new adaptive method has been amalgamated with multistep nonlinear predictive control techniques to form an adaptive neural controller. The performance of this controller is demonstrated, and evaluated using two simulated realistic processes; level control of a conical tank and multivariable control of an industrial evaporator. The results indicate that these techniques have good practical potential for the adaptive control of nonlinear processes.

ISSN:0020-7179    

DOI:10.1080/00207179408921516

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In this paper we first study the normalized right and left coprime factorizations of a nonlinear system from a state-space point of view. In order to do so, we introduce the notion of inner and co-inner nonlinear systems. Secondly we deal with balancing for unstable nonlinear systems. For linear systems there are several ways to approach this problem, and we generalize the ideas of balancing the normalized coprime factorization and of LQG balancing to the nonlinear case. LQG balancing can be seen as measuring the influence of a state component on a certain future and past energy function. We extend this interpretation to the nonlinear case. Furthermore we use the normalized coprime factorization to give another way of balancing the unstable nonlinear system. We give the relation between these two methods of balancing, which is similar to the relation in the linear case.

ISSN:0020-7179    

DOI:10.1080/00207179408921517

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A discrete quasi-autoregressive moving average (QARMA) model and an equivalent impulse response (IR) description are established for linear continuous systems with internal and external point delays which are discretized through a sampler and zero-order-hold device. The QARMA-model is proved to differ from the standard autoregressive moving average (ARMA) models because of its infinite input memory caused by the delays. Based on the IR-model, a finite impulse response (FIR)-filter is proposed to approximate the input-output description under exponential stability of the unforced system. Its implementation is discussed by using fast filtering design tools.

ISSN:0020-7179    

DOI:10.1080/00207179408921518

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A decoupled full-dimension form is introduced for state models. In this form, the dimension of the state vector is time-invariant, which is equal to the dimension of the state-space at each time instant. Therefore, the dimension of the state vector is minimized from the time-variant point of view and all the state variables are independent. Moreover, the state vector in a state model of the decoupled full-dimension form is partitioned into two decoupled subvectors, each of which alone forms a subsystem. One of the subsystems is an FIR system whose state vector is dependent only on inputs at (finitely) past instants. In addition, this subsystem is completely reachable. The other subsystem is an IIR system whose state-space is equal to the force-free solution set of the state vector of the subsystem. It is proved that every state model in the conventional form can be mapped by a linear one-to-one map into an equivalent state model in the decoupled full-dimension form. In comparison with a state model in the conventional form, the one in the decoupled full-dimension form has the advantages that the dimension of its state vector clearly shows the state-space and the set of all possible states for prescribed past inputs. This avoids erroneous conclusions resulting from including or selecting a state that the system does not own. The proposed decoupled full-dimension form, which suggests a new realization form of the input-output map, is consequently a convenient tool for studying LTV systems.

ISSN:0020-7179    

DOI:10.1080/00207179408921519

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor